Many surface parameters have been suggested to influence blood-materials interactions, for example, interfacial free energy, surface group mobility and surface charge. Our preliminary test results suggest that surface charge greatly enhances blood compatibility. We propose to expand these studies to define the extent and limitations of ion containing polymers - blood interactions. We will also correlate plasma protein adsorption with blood interactions. This study will be done using agarose gels which have high water content (greater than 96 percent water) and very minimal protein interactions. The agarose gels will be systematically derivatized with hydrophobic and charged groups using published procedures. Serum protein adsorption to these surfaces will be measured by chromatographic and electrophoretic techniques. Comparable agarose surfaces will be prepared and studied using a battery of in vitro blood tests. These blood studies include tests of whole blood clotting times, intrinsic activation, extrinsic activation, platelet adhesion, and platelet activation. It is expected that these studies will give insight between the nature of certain surface parameters and blood interactions.